1. Field of the Invention
The present invention relates to a technology for manufacturing an array substrate of a liquid crystal display, and in particular to a storage capacitor having an increased aperture ratio and method of manufacturing the same.
2. The Prior Arts
In an active matrix liquid crystal display (LCD), each pixel is provided with a thin-film-transistor (TFT), wherein each TFT includes a gate electrode connected to a scanning line in a horizontal direction, a source electrode connected to a data line in a vertical direction, and a drain electrode connected to a liquid crystal capacitance.
When a thin-film-transistor is turned-on, there will be no current flow through the liquid crystal, and the liquid crystal will react to an electric field caused by the charges accumulated on both sides of liquid crystal, so that the voltage difference between these charges would hereby affect the gray level illuminance of pixels on a panel. Thus, it would be a matter of great importance in stressing the problem of how to reduce the leakage current of liquid crystal capacitance. In order to solve the above-mentioned problem, it is practicable to form a storage capacitor on a glass substrate, which is parallel-connected with the liquid crystal capacitance. In general, the storage capacitor is obtained through a series of procedures that includes forming a metal layer, a first dielectric layer, a second dielectric layer and an electrode layer on a glass substrate, wherein the first dielectric layer, the second dielectric layer and the electrode layer are respectively shared a uniform thickness with other layers of the elements on a substrate.
The application of the storage capacitor may reduce the voltage variations caused by leakage current of liquid crystal capacitance, hereby increasing the capacity of potential-holding. In addition, the application of a storage capacitor may reduce the coupling effects between capacitors as well. From this point of view, the storage capacitor should be designed as large as possible, however, the size of the storage capacitor may not be enlarged without any limits in practice. Since the storage capacitor is made by sandwiching an insulation layer between two metal electrodes, yet since the light can not be transmitted through the metal layer, therefore, once the storage capacitor is designed in a larger scale, the larger area of the light will be shielded by the enlarged area of the storage capacitor, so that the aperture ratio and light transmittance are reduced. However, on the other hand, if an increased aperture ratio is essentially required, the storage capacitor would have to be made smaller, which may further reduce its capability of potential-holding and capacitance coupling effects improvement.
Due to the above-mentioned shortcomings and drawbacks, the present invention discloses a storage capacitor having an increased aperture ratio and a method of manufacturing the same, thus solving the contradiction of the prior art.